// A listener that can change the L&F of a frame based on the actionCommand of an 
// ActionEvent object. Supported L&Fs are: Mac, Metal, Motif, and Windows. Not all
// L&Fs will be available on a given machine. Notably, the Mac and Windows L&Fs work 
// only on their specific platforms.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class LnFListener implements ActionListener {
  Frame frame;

  public LnFListener(Frame f) {
    frame = f;
  }

  public void actionPerformed(ActionEvent e) {
    String lnfName = null;
    if (e.getActionCommand( ).equals("Mac")) {
      lnfName = "com.apple.mrj.swing.MacLookAndFeel";
    } else if (e.getActionCommand( ).equals("Metal")) {
      lnfName = "javax.swing.plaf.metal.MetalLookAndFeel";
    } else if (e.getActionCommand( ).equals("Motif")) {
      lnfName = "com.sun.java.swing.plaf.motif.MotifLookAndFeel";
    } else if (e.getActionCommand( ).equals("Windows")) {
      lnfName = "com.sun.java.swing.plaf.windows.WindowsLookAndFeel";
    } else {
      System.err.println("Unrecognized L&F request action: " +
        e.getActionCommand( )); 
      return;
    }
    try {
      UIManager.setLookAndFeel(lnfName);
      SwingUtilities.updateComponentTreeUI(frame);
    }
    catch (UnsupportedLookAndFeelException ex1) {
      System.err.println("Unsupported LookAndFeel: " + lnfName);
    }
    catch (ClassNotFoundException ex2) {
      System.err.println("LookAndFeel class not found: " + lnfName);
    }
    catch (InstantiationException ex3) {
      System.err.println("Could not load LookAndFeel: " + lnfName);
    }
    catch (IllegalAccessException ex4) {
      System.err.println("Cannot use LookAndFeel: " + lnfName);
    }
  }
}
